Danburiitti / Danburite
Alkuperä (todennäköinen) : Mexico
Paino ( ct noin ) : 0,5
Mitat ( mm noin ) : 5 x 5 x 3,5
Hionta : viistehiottu
Puhtaus : TL
Erinomainen Erittäin hyvä Hyvä ”kakkosluokkaa”
Ominaista : Kirkas väritön timanttimainen danburiitti,
hakusanoja: danburiitti,utuinen ,väritön,pyöreä
|Danburite is a calcium borosilicate Ca(B2Si2O8) that was first discovered in Danbury, Connecticut. The original deposit is now buried under the city of Danbury.|
|Color Key:||White, yellowish, very light pink, buff colored, very light brown.|
|Pleochroism:||1.630(+.003,-.003) - 1.636 (+.003, -.003)|
|Chemical Composition:||calcium borosilicate|
|Ocurrence:||Danbury, Connecticut and Russell, New York, USA; Charcas, San Luis Potosi, Mexico; Kyushu Island, Japan; Mogok, Burma and Uri, Switzerland; Madagascar.|
|With a hardness of 7, danburite is quite hard and suitable for any kind of jewelry. Because of it’s high refractive index, well cut danburites are remarkably bright and can look something like diamonds. It is normally colorless to very light pink in color but some deposits may produce stones which can be shades of yellow or brown. Danburite handles easily and ordinarily offers no problems for lapidaries. It makes an especially brilliant gem because of its extreme clarity.|
The luster is vitreous, and the cleavage is poor in one direction, -basal. The fracture is uneven to conchoidal and the streak is white or colorless. Crystal habits include generally prismatic crystals with a diamond-shaped cross-section. The terminations are steeply slanted producing a wedge like look.
Primarily in metamorphosed limestones but also in low-temperature hydrothermal veins with sulfides and calcite. Associated Minerals include quartz, feldspars, cassiterite, dolomite, corundum, fluorite, iron sulfides, and calcite.
The bulk of todays danburite production is from the Charcas mineral district in the state of San Luis Potosi in Mexico. The deposit was discovered in 1574 and has been worked ever since for lead, zinc, copper and silver. The metal ore deposits are found in veins along faults in shales, limestones, volcanics, and monzonites. The danburite is a byproduct of the metal ore production. Well shaped and clean crystal terminations over twenty-five carats are rare and most pieces are average around ten carats.
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